1. Field of the Invention
The present invention relates generally to liquid collection and transfer system, and more particularly to liquid waste control systems for semiconductor fabrication processes.
2. Description of the Prior Art
The collection of depleted and contaminated chemicals from chemical processing equipment is an important facet of all manufacturing processes that utilize such chemicals. Where hazardous waste chemicals are not properly controlled, the manufacturing facilities that utilize the chemicals can be shut down, resulting in significant and expensive losses of material and equipment. Also, high levels of volatile organic compounds (VOCs) can be generated by waste chemicals, and the control of such VOCs is a significant problem. Therefore, a need exists for reliable, low VOC producing waste chemical collection systems, and particularly systems that have automated strategies to prevent system shutdown where serious alarm conditions occur.
Many automated liquid transfer systems exist, and generally, the utilization of such systems to transfer chemicals is known. However, where particularly sensitive chemical processing steps are being conducted, liquid transfer systems that utilize pumps and other reciprocating, vibration causing devices should be avoided. Liquid transfer systems, such as are described in U.S. Pat. Nos. 5,148,945, issued Sep. 22, 1992 to Gaetz, and 5,330,072, issued Jul. 19, 1994 to Ferri and Gaetz are then effectively utilized in such systems. However, even where such a liquid transfer system is utilized, an unacceptable high VOC production level can occur, and an alarm event, such as a full waste collection tank, can cause the entire chemical process to be shut down. A strategy, which allows the chemical processing system to continue in operation while the full waste tank alarm condition is solved is therefore desirable. A preferred embodiment of the present invention provides such an alarm condition strategy.